The present invention relates generally to vehicle communication systems, and more particularly to a method and apparatus for communicating between multiple vehicles in close proximity to each other.
Collision countermeasure and warning systems are becoming more widely used. These systems detect objects or vehicles within close proximity of a vehicle and perform safety operations to prevent or minimize the likelihood of a collision and any resulting injury to an occupant.
Through the development of collision countermeasure and warning systems, vehicle-to-vehicle communications have been suggested for increased vehicle awareness of other vehicles or potentially hazardous conditions that may exist within close proximity to the vehicle.
Vehicle-to-vehicle communication for safety purposes requires several distinct types of data communication. It would be beneficial if a vehicle was aware of other vehicles that may be approaching from multiple directions and at various velocities. It would also be beneficial if a vehicle was aware of various traffic conditions, such as a slow moving congested traffic situation versus a clear faster moving situation when a first vehicle may pass a second vehicle. Thus, it would be advantageous if a vehicle in motion was able to discover and communicate with other vehicles that are traveling in a concurrent manner, including vehicles approaching from a forward, rearward, or lateral direction of a first vehicle.
Traditional vehicle communication systems have a vehicle time delay discovery problem. The greater the relative speed of the vehicles, and the shorter the range of the Bluetooth devices, the more significant the synchronization time delay.
Traditional vehicle communication systems discover vehicles in close proximity under slow moving traffic conditions. Generally, during a slow moving traffic condition, vehicles tend to remain in a vehicle range for a longer period of time, allowing the vehicle to discover the other vehicles without any timing issues.
The synchronization time delay is quite evident when vehicles approach head-on because the relative speed is large and the possibility exists that they will not synchronize before they pass. It is also quite evident when the vehicles move lateral to each other because objects off the road may interfere with the signal.
The lateral approaching vehicle situation introduces an additional problem with existing vehicle communication systems. Objects between the first vehicle and the approaching vehicle may block communication signals and make detecting laterally approaching vehicles difficult. Thus, network communication is crucial to provide advanced warning of objects or potential hazards to vehicles within the network.
Ad hoc wireless mobile networks are commonly used because of their associated desirable benefits for vehicle-to-vehicle data communication including: lack of reliance on third party infrastructures, ability to adapt to local conditions readily, ability to allocate resources on a local level, and absence of single points of failure. Also, commodity implementations of ad hoc networking hardware are readily available and well proven. However, ad hoc wireless mobile networks have disadvantages associated with routing of communication signals.
Many pre-crash and crash avoidance technologies require knowledge of a vehicle location and velocity with respect to locations and velocities of other nearby vehicles. Global Positioning Systems (GPS) provide this type of information, but frequently without the necessary accuracy.
Current GPS require twenty-four operational satellites to guarantee that there are at least four above the horizon for any point on Earth at any given time.
Currently, GPS devices are connected to a computer in a vehicle equipped with a two-way digital radio for communicating with the vehicles around it. Position, Velocity and Time (PVT) data is computed in the GPS and passed to the computer, typically using the National Marine Electronics Association (NMEA) standards. The computed PVT data is exchanged between vehicles using two-way digital radios, wireless modems, or network devices such as those conforming to the IEEE 802.11, 802.1 la, or 802.1 lb specifications. The known position and velocity vectors are subtracted to give the relative velocity vectors.
The errors attributed to the OPS receivers have not been eliminated in this way, however, and these errors are multiplied in the position calculation because they are quite sensitive to the geometric relationship between the satellites that are being used. Further, each vehicle GPS must be able to receive signals from at least four satellites simultaneously for the method to work. Buildings, overpasses and foliage may limit the number of satellite xe2x80x9cvisiblexe2x80x9d to the receivers. These factors all reduce the effectiveness of this approach as a solution to vehicle positioning for the purposes of vehicle safety, navigation and Telematics.
It would therefore be desirable to develop a wireless mobile communication network for vehicle-to-vehicle communication that is feasible to implement for various approaching vehicle situations, that overcomes the above mentioned timing and accuracy issues.
The present invention provides a method and apparatus for communicating between multiple vehicles in close proximity to each other. In accordance with one aspect of the present invention, a relative vehicle positioning system for a first vehicle includes a GPS antenna adapted to receive satellite signals generated in response to relative vehicle positioning and generate therefrom a GPS signal. A first Bluetooth radio is adapted to exchange bearing information with a second vehicle and generate therefrom a PVT signal. A GPS unit including a controller is adapted to receive the GPS signal and the PVT signal, and generate therefrom, a GPS-Bluetooth relative position signal.
In accordance with another aspect of the present invention, a method of communicating between vehicles having GPS-Bluetooth devices is provided. The method includes receiving timing and vehicle data, generating a GPS signal, computing range and velocity through Doppler shift, sharing information between the Bluetooth devices, and synchronizing the GPS-Bluetooth devices.
The GPS-Bluetooth system in the present invention improves GPS for vehicle navigation and other purposes as well as vehicle safety and pre-crash sensing.
Furthermore, the present invention utilizes multiple vehicle technologies that are widely available to minimize additional costs to a vehicle system.
Other advantages and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.